What are "Ovedei Fishtim"?
Rashi: They plant flax by the river.
Radak: This is people who make flax. Also "Lachen Yakir Mabadeihem" (Iyov 34:25) is like Ma'aseihem.
Malbim: The Egyptians used to profit from flax, which grew in abundance there. The best linen was in Egypt. This will cease, and those who worked with flax will be ashamed.
What are "Serikos"?
Rashi: It is flax; they comb it and weave "Chorai" (fish traps) from it (Radak - from the best flax), which are made full of Chorim (holes).
Radak: It is the best flax.
Why does it say "Chorai"?
Rashi: (It is as if it says Chorim.) This is like "Bahamos Sadai" (Tehilim 8:8; it is as if it says Sados), "v'Kara Lo Chalonai" (Yirmeyah 22:14, is like Chalonim).
Radak, Malbim: They are white garments (made from flax).